Soldering problem

[DIYspanner]

I have a AT8 brand magnifier with secondary batteries soldered on to the PCB.

The problem is one of the battery lugs has broken and its proving difficult to get solder to take to the face of the battery cap.

Is there a particular type of solder I should use?
The solder I have is general purpose.

 

[bernardgreen]

Are the tags soldered or spot welded to the battery. ?

If spot welded then the metal of the battery may be one that cannot be soldered with normal soldering such as aluminium or stainless steel.

And if they are soldered then care is needed to ensure the battery is not over heated.

Replacing with a new tagged cell may be cost effective. They look to be standard AA cells. Keep as much of the tags flexible when soldering to the PCB

https://uk.rs-online.com/web/p/aa-rechargeable-batteries/7760835/

https://www.maplin.co.uk/p/tagged-nimh-aa-2000mah-single-battery-l25ar

Other sources are available

 

[DIYspanner]

Thanks for posting!

I hadn't considered that the lugs could be welded. Presumably the lugs were welded to the caps before battery assembly to avoid damages by heat.

The batteries are AAA size so I just need to work the rating of them (no marking on them) to get a new one with welded lugs.

The DC charger has a 9V output and there are x2 batteries on both side of the PCB.

 

[bernardgreen]

The AAA cells from RS components

https://uk.rs-online.com/web/p/aaa-rechargeable-batteries/7760831/

are 800mAh and would most likely be OK. If the capacity is larger than the present cells then the charging would take more time.

If you cannot ascertain the capacity of the present cells then and are replacing one which may be a different capacity then it is sensible to replace all cells to ensure they all charge to the same level.

 

[DIYspanner]

I'll get a pack of high Ah from ebay, a x4 pack for the price of one from maplin/RS.

Thanks for the info on the connections, much appreciated.

 

[bernardgreen]

http://coil.co.uk/products.html may be able to provide details about the cell capacity.

 

[winston1]

There appears to be a little bit of lug left on the battery. You should be able to solder a bit of wire to this rather than the battery end cap.

 

[DIYspanner]

Sadly, the lug's off the end cap completely.

What you can see is a drop of solder that's stuck to the cap.

I've tried several time to solder and its come loose every time.

I'll get a new set tagged batteries and solder them in.

 

[bernardgreen]

able to solder a bit of wire to this rather than the battery end cap.

If the "bit of lug" is made hot enough for a secure solder joint then the heat conducted along the tag ( lug ) and into the case of the cell will be significant and then possibly damaging to the cell

 

[DIYspanner]

These are a good price!

They have a website so are a proper brand.

 

[Keithmac]

Maybe glue or strap/ tape your new batteries down to avoid stressing the tabs and having the same failure again?.

 

[DIYspanner]

Called in the local Maplins yesterday to get a pack of x6 800Ah which they told me over the phone they had in stock.

Get there, they don't stock a x6 pack and didn't have a x1 in either.

Got a couple of x4 packs of AAA 950Ah off ebay instead.

 

[DIYspanner]

Job done!

The tagged AAAs I got of ebay seem good quality and I now have a working LED light on the magnifier.

Thanks all for posting.

 

[plugwash]

AIUI the tabs are normally spot welded on by passing a large electrical current through small probes. Locally the metal in contact with the probe gets extremely hot and melts and mechanical pressure on the probes forces the molton metal onto the battery.